/Engine/Source/Runtime/MeshDescription/Public/MeshDescriptionBase.h
Returns reference to an array of VertexInstance IDs forming the perimeter of this polygon
void GetPolygonVertexInstances ( [FPolygonID](API\Runtime\MeshDescription\FPolygonID) PolygonID, [TArray](API\Runtime\Core\Containers\TArray)< [FVertexInstanceID](API\Runtime\MeshDescription\FVertexInstanceID) > & OutVertexInstanceIDs ) const